Characterizations of tropospheric turbulence and stability layers from aircraft observations
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Choetal-2003.pdf
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Author(s)
Cho, John Y. N.
Newell, Reginald E.
Anderson, Bruce E.
Barrick, John D. W.
Thornhill, K. Lee
Date Issued
August 2003
Journal
Journal of Geophysical Research
Publisher
American Geophysical Union (AGU)
Citation
Cho, John Y. N. et al. “Characterizations of Tropospheric Turbulence and Stability Layers from Aircraft Observations.” Journal of Geophysical Research 108, D20 (October 2003): 5 © 2003 American Geophysical Union
Version
Final published version
Abstract
[1] Velocity, temperature, and specific humidity data collected by aircraft at 20-Hz resolution are analyzed for stability and turbulence parameters. Over 100 vertical profiles (mostly over the ocean) with a total of over 300 km in vertical airspace sampled are used. The compiled statistics show that anisotropy in the velocity fluctuations prevail down to the smallest spatial separations measured. A partitioning of convective versus dynamical instability indicates that in the free troposphere, the ratio of shear-produced turbulence to convectively produced turbulence increases from roughly 2:1 for weak turbulence (ϵ < 10⁻⁴ m² s⁻³) to perhaps 3:1 for strong turbulence (ϵ > 10⁻⁴ m² s⁻³). For the boundary layer, this ratio is close to 1:1 for weak turbulence and roughly 2:1 for strong turbulence. There is also a correlation between the strength of the vertical shear in horizontal winds and the turbulence intensity. In the free troposphere the turbulence intensity is independent of the degree of static stability, whereas in the boundary layer the turbulence intensity increases with a fall in static stability. Vertical humidity gradients correlate with static stability for strong humidity gradients, which supports the basic notion that stable layers impede vertical mixing of trace gases and aerosols. Vertical shear correlates with vertical humidity gradient, so it appears that the effect of differential advection creating tracer gradients dominates the effect of differential advection destroying tracer gradients through shear-induced turbulence.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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DOI of Published Version
https://doi.org/10.1029/2002JD002820
